Fix frozen status loss when moving objects

[Bug #19536]

When objects are moved between size pools, their frozen status is lost
in the shape. This will cause the frozen check to be bypassed when there
is an inline cache. For example, the following script should raise a
FrozenError, but doesn't on Ruby 3.2 and master.

    class A
      def add_ivars
        @a = @b = @c = @d = 1
      end

      def set_a
        @a = 10
      end
    end

    a = A.new
    a.add_ivars
    a.freeze

    b = A.new
    b.add_ivars
    b.set_a # Set the inline cache in set_a

    GC.verify_compaction_references(expand_heap: true, toward: :empty)

    a.set_a

2 files changed, 29 insertions, 1 deletions

diff --git a/shape.c b/shape.c
index 01ec0f0604..e264e7bee5 100644
--- a/shape.c
+++ b/shape.c
@@ -451,6 +451,7 @@ rb_shape_traverse_from_new_root(rb_shape_t *initial_shape, rb_shape_t *dest_shap
 
     switch ((enum shape_type)dest_shape->type) {
       case SHAPE_IVAR:
+      case SHAPE_FROZEN:
         if (!next_shape->edges) {
             return NULL;
         }
@@ -464,7 +465,6 @@ rb_shape_traverse_from_new_root(rb_shape_t *initial_shape, rb_shape_t *dest_shap
         }
         break;
       case SHAPE_ROOT:
-      case SHAPE_FROZEN:
       case SHAPE_CAPACITY_CHANGE:
       case SHAPE_INITIAL_CAPACITY:
       case SHAPE_T_OBJECT:
diff --git a/test/ruby/test_gc_compact.rb b/test/ruby/test_gc_compact.rb
index 72d79be037..bef2ba9605 100644
--- a/test/ruby/test_gc_compact.rb
+++ b/test/ruby/test_gc_compact.rb
@@ -416,4 +416,32 @@ class TestGCCompact < Test::Unit::TestCase
       assert_include(ObjectSpace.dump(ary[0]), '"embedded":true')
     end;
   end
+
+  def test_moving_objects_between_size_pools_keeps_shape_frozen_status
+    # [Bug #19536]
+    assert_separately([], "#{<<~"begin;"}\n#{<<~"end;"}")
+    begin;
+      class A
+        def add_ivars
+          @a = @b = @c = @d = 1
+        end
+
+        def set_a
+          @a = 10
+        end
+      end
+
+      a = A.new
+      a.add_ivars
+      a.freeze
+
+      b = A.new
+      b.add_ivars
+      b.set_a # Set the inline cache in set_a
+
+      GC.verify_compaction_references(expand_heap: true, toward: :empty)
+
+      assert_raise(FrozenError) { a.set_a }
+    end;
+  end
 end